The present invention pertains to methods for drying confection pieces, and in particular to methods for drying confection pieces having outer surfaces which are adhesive at elevated temperature and moisture levels.
Aerated confection products, such as nougat, marshmallow and the like, have long been recognized for their unusual difficulty in drying, due to their easily deformable aerated structure, adhesive nature, the ease with which an adhesive bond is made upon contact with the confection product and the strength of the bond, particularly when the bond is formed between two confection pieces. The problems are, of course, aggravated by processing of smaller-size confection pieces having a high volume density.
Aerated confection products such as hard marshmallow bits, of the types used in breakfast cereals and the like, are typically extruded at temperatures above ambient temperature from an aerated syrup, in the form of ribbon-like strands The extruded ribbon-like strands of marshmallow have a relatively high moisture content which must be greatly reduced by drying. Unlike other marshmallow products, these bits are dried to lower moisture levels, to blend with the dry breakfast cereal, and are rehydrated when milk is added.
Prior to drying and cutting, the marshmallow strands are relatively soft and exhibit, even prior to heating, an adhesive or gummy surface. In order to facilitate conveying of the marshmallow strands to a cutting station and thereafter to a drying station, the extruded marshmallow strands are coated with starch to provide a barrier on their outer surface which reduces adhesive engagement with other marshmallow strands and with equipment such as conveyor belts, which they may contact. Further, as the marshmallow strands are cut into individual pieces or bits, the surfaces formed by cutting are coated with starch to prevent agglomeration among the bits, as well as adhesion to equipment which conveys or otherwise handles the marshmallow pieces. The marshmallow pieces are now ready for drying, the final step in their production.
Prior to the present invention, it was believed necessary to form an outer crust on the marshmallow pieces relatively slowly, and at relatively low but elevated temperatures, prior to heating those pieces to a higher temperature. The crust prevents pieces contacting each other from subsequently adhering to each other in an agglomerated mass, as the marshmallow outer surface is further softened and becomes even more adhesive as its temperature is raised. The crust-forming operation, as well as the subsequent drying operation at higher temperatures, is deliberately slow and relatively inefficient, requiring a considerable amount of floor space and large machinery for carrying out an extended, multistage drying process. Presently, the crust-forming operation requires a first production line in which the outer surfaces of the freshly cut marshmallow pieces are slowly dried on a conveyor belt at low temperatures. The major bulk of each marshmallow piece is relatively unaffected by the crust-forming operation, and accordingly, substantially the entire process of drying the marshmallow pieces must still be performed. To carry out the drying operation, the marshmallow pieces are transferred from the first production line to a second production line which uses a compartmented conveyor system for step-wise drying of the marshmallow pieces at successively higher drying temperatures. After drying, the marshmallow pieces are still relatively soft, unable to support an appreciable weight without a crushing deformation, and oftentimes a subsequent agglomeration occurs if contact is maintained long enough. Accordingly, the marshmallow bits are cooled.
Various arrangements for handling materials having a cohesive quality have been proposed. For example, U.S. Pat. No. 3,511,843 describes a fluidized bed conveyor for damp ground tobacco which fluidizes the tobacco material with steam. The arrangement employs mechanical agitation to avoid perforation of individual tobacco shreds by forming passages around pieces of the tobacco material for the conveying steam, without forcing the steam through fragments of the tobacco material. This patent is concerned with the transporting of tobacco material, using steam as the fluidizing gas and is not concerned with confection products or with the moisture content of the material conveyed.
Other fluidized gas arrangements have also been proposed. One arrangement, for example, is used to agglomerate coffee particles to produce larger-sized coffee "chunks." The arrangement introduces coffee particles into a fluidized bed which promotes cohesion of the coffee particles.
Accordingly, it is an object of the present invention to provide a method for drying and cooling aerated confection pieces, such as nougat, marshmallow bits and the like, in a bulk process, without causing agglomeration of those bits and while preventing adhesion of those bits to machinery which they may contact.
Yet another object of the present invention is to provide a method for drying and cooling marshmallow bits by imparting to those bits a plurality of different modes of movement throughout the drying cycle, with reduced processing times, while reducing the floor space and energy input previously required.
These and other objects and advantages of this invention will be apparent from the following detailed description and the accompanying drawings.